Variability in symbiotic nitrogen fixation among white landraces of common bean from the Iberian peninsula
Résumé
Common bean is considered to have a low capacity of symbiotic nitrogen fixation (SNF) with rhizobia in Europe. However, genetic variability for SNF among bean germplasm has been found in the regions of origin of this species. The objective of this research was to search for European bean germplasm with high SNF capacity. For this purpose, the N-2-dependent growth of various bean accessions, belonging to the great northern, caparron, white kidney and canellini market classes, was compared in glasshouse, under optimized symbiotic conditions with a Rhizobium tropici inoculant. In the studied germplasm, genotypic variation was found for (i) nodulation with PHA0184, PHA-0267, PHA-0290, PHA-0034 and PHA-0276 having the highest nodule biomass, (ii) N-2-dependent plant-growth with PHA-0013, PHA-0014, PHA-0290 and PHA-0838 having the highest shoot biomass and (iii) the ratio of the shoot growth as a function of nodule growth with PHA-0034, PHA-0053, PHA-0184, PHA-0267 and PHA-0276 having the highest value. It is concluded that the accessions PHA-0013, PHA-0014, PHA-0034 and PHA-0053 from the Iberian peninsula could be recommended for further improvement of the SNF potential in the common bean varieties currently grown in Europe.